The present invention relates to an electrically conductive member in the form of a belt, a roller, a drum, a blade, etc. which is used in an image-forming apparatus, such as a copying machine, an electrophotographic apparatus including a laser printer, an ink jet printer, a toner let printer, a thermal transfer printer, a thermal sublimation printer, and an impact printer.
A related art image-forming apparatus, such as the coping machine and the printer, are equipped with such members as a belt, a roller, a drum, a blade, etc. for charging, development, transfer, intermediate transfer, toner layer forming, toner conveying, toner stirring, cleaning, fixing, and paper carrying.
These members are usually required to be soft and hence are formed from an electrically conductive rubbery elastic body or cellular body which is optionally mixed with metal or fiber or laminated with resin molding. In addition, these members formed from a rubbery elastic body or cellular body have their surface coated with a resin layer for various objects, such as protecting the photosensitive body from staining, preventing the toner from sticking to the photosensitive body, controlling the toner charging, and adjusting the resistance and frictional characteristics.
Unfortunately, the resin coating layer is by far harder than rubber or the like and hence does not conform easily to the elastic deformation of rubber. As the result, it cracks when formed on a belt or roller and such cracks permit rubber ingredients to ooze out or permit toner particles to stick to them. Besides, the coating layer changes in frictional characteristics due to cracking, and thus, these troubles lead to failure to achieve the desired object in early stages. Particularly, the life of the coating layer is a serious problem in the case of belt-like or drum-like members which need a higher degree of deformability than any other members. A conceivable way to address this problem is to form the coating layer from a polyurethane resin which has a comparatively good flexibility. Although a polyurethane resin easily conforms to the elastic deformation of rubber, it is not satisfactory in its ability to protect the photosensitive body from staining, to prevent the toner sticking, and to reduce the coefficient of friction. Therefore, it does not fully achieve the object of the coating layer.